For GDI cleaning, get the aerosol seafoam and spray it directly into the intake by sticking the straw past the butterfly valve.
That should at least help the backs of the valves a little bit. I am guessing you would have to do this procedure pretty often, say every 10,000 miles or so, in order to keep them clean. Seafoam is pretty weak sauce by today's standards.
11 Chevy Silverado - PP 5w-30
10 Ford Focus - QSAD 5w-20
14 Yamaha Super Tenere - Delo 15w-40